Thread: Isolation level in a function

Isolation level in a function

From
"bgolda"
Date:
Hello, this is my first post, please don't shoot...

I was just experimenting with transactions (PG 8.1), and there is
something which puzzles me. If i write 'SET TRANSACTION ISOLATION LEVEL
SERIALIZABLE;' in my function, it breaks. Error informs me, that it was
executed after some query, while it is a first command in the function
after declares and begin!

However, it seems to work perfectly well if I change in the same place
the system variable, responsible for the transaction level. I used
set_config, if I remember well. The function is only for a DBA task, so
it seems to be all right to use set_config, isn't it?

And my questions are:
1) Why in the first case it is not possible? Is it an error or am I
just doing something wrong? Should have set something before?
2) Are there any downsides of the mentioned solution (changing
transaction_isolation value), except of the fact that it is an
administration command and should not be used :)?

Thanks,

_-_-_-_
Bart Golda


Re: Isolation level in a function

From
Bruno Wolff III
Date:
On Thu, Jan 19, 2006 at 02:05:41 -0800,
  bgolda <e9syuk002@sneakemail.com> wrote:
> Hello, this is my first post, please don't shoot...
>
> I was just experimenting with transactions (PG 8.1), and there is
> something which puzzles me. If i write 'SET TRANSACTION ISOLATION LEVEL
> SERIALIZABLE;' in my function, it breaks. Error informs me, that it was
> executed after some query, while it is a first command in the function
> after declares and begin!

Because there is already a transaction which the function is executing in
and for which a query has been started (e.g. the one that calls the function).

> However, it seems to work perfectly well if I change in the same place
> the system variable, responsible for the transaction level. I used
> set_config, if I remember well. The function is only for a DBA task, so
> it seems to be all right to use set_config, isn't it?
>
> And my questions are:
> 1) Why in the first case it is not possible? Is it an error or am I
> just doing something wrong? Should have set something before?
> 2) Are there any downsides of the mentioned solution (changing
> transaction_isolation value), except of the fact that it is an
> administration command and should not be used :)?
>
> Thanks,
>
> _-_-_-_
> Bart Golda
>
>
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